In case you are still interested, here are my answers:
a) ID: 4163\N905C Rev:110
b) Bought in New York, using in Hungary
c-d) updated at least once via desktop, wifi and manual-usb too, the updates were always successful in all method, however the well-known bugs appeared (slow page turn, wrong cover, font issues etc.)
My Kobo is ad-supported, but as long as it's not syncronised via destop or wifi, it behaves as a "regular" device.